As for the ambient temps in the winter, I live in a big drafty apartment and to avoid my gas bill from going through the roof I keep my apartment at about 70 degrees. On the colder days, I use a CHE on a dimmer to keep temps inside the enclosure (the tank...don't ave any issue in my tubs or rack...) warm enough without killing too much humidity.

I can' help you with a vet as I'm not from the area, just call around. The most you'll need unless the snake gets sick is a fecal test done to make sure they are clean of parasites.

As for buying online, there are TONS of breeders, even on this website, kingsnake.com, faunaclassifieds.com...just make SURE you check out other people experiences and ratings before you buy.

Congrats on your decision and good luck! Welcome to the forum